On 2021/1/7 7:46, Kees Cook wrote:
subject typo: "sysclt" -> "sysctl" On Thu, Dec 24, 2020 at 03:42:56PM +0800, Xiaoming Ni wrote:The process_sysctl_arg() does not check whether val is empty before invoking strlen(val). If the command line parameter () is incorrectly configured and val is empty, oops is triggered. For example, "hung_task_panic=1" is incorrectly written as "hung_task_panic". log: Kernel command line: .... hung_task_panic .... [000000000000000n] user address but active_mm is swapper Internal error: Oops: 96000005 [#1] SMP Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.10.1 #1 Hardware name: linux,dummy-virt (DT) pstate: 40000005 (nZcv daif -PAN -UAO -TCO BTYPE=--) pc : __pi_strlen+0x10/0x98 lr : process_sysctl_arg+0x1e4/0x2ac sp : ffffffc01104bd40 x29: ffffffc01104bd40 x28: 0000000000000000 x27: ffffff80c0a4691e x26: ffffffc0102a7c8c x25: 0000000000000000 x24: ffffffc01104be80 x23: ffffff80c22f0b00 x22: ffffff80c02e28c0 x21: ffffffc0109f9000 x20: 0000000000000000 x19: ffffffc0107c08de x18: 0000000000000003 x17: ffffffc01105d000 x16: 0000000000000054 x15: ffffffffffffffff x14: 3030253078413830 x13: 000000000000ffff x12: 0000000000000000 x11: 0101010101010101 x10: 0000000000000005 x9 : 0000000000000003 x8 : ffffff80c0980c08 x7 : 0000000000000000 x6 : 0000000000000002 x5 : ffffff80c0235000 x4 : ffffff810f7c7ee0 x3 : 000000000000043a x2 : 00bdcc4ebacf1a54 x1 : 0000000000000000 x0 : 0000000000000000 Call trace: __pi_strlen+0x10/0x98 parse_args+0x278/0x344 do_sysctl_args+0x8c/0xfc kernel_init+0x5c/0xf4 ret_from_fork+0x10/0x30 Code: b200c3eb 927cec01 f2400c07 54000301 (a8c10c22) Fixes: 3db978d480e2843 ("kernel/sysctl: support setting sysctl parameters from kernel command line") Signed-off-by: Xiaoming Ni <nixiaoming@xxxxxxxxxx> --- fs/proc/proc_sysctl.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index 317899222d7f..4516411a2b44 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -1757,6 +1757,9 @@ static int process_sysctl_arg(char *param, char *val, loff_t pos = 0; ssize_t wret;+ if (!val)+ return 0; + if (strncmp(param, "sysctl", sizeof("sysctl") - 1) == 0) { param += sizeof("sysctl") - 1;Otherwise, yeah, this is a good test to add. I would make it more verbose, though: if (!val) { pr_err("Missing param value! Expected '%s=...value...'\n", param); return 0; }
Yes, it's better to add log output. Thank you for your review. Do I need to send V2 patch based on review comments? Thanks Xiaoming Ni
